Science, with a side of humility

After 40 years of warning Americans to avoid cholesterol-rich foods, the nation’s top nutrition panel is poised to tell the public, in effect, “never mind.”

The Dietary Guidelines Advisory Committee, which shapes authoritative federal nutritional recommendations, has concluded that there is insufficient evidence to back up its long-standing 300-milligram-per-day limit on cholesterol intake, The Post reported last week.

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Cholesterol in the blood remains a heart disease risk factor. It’s just that consuming the stuff in the form of, say, shrimp scampi or a large omelette doesn’t seem to raise those levels, as previously thought.

So much, perhaps, for the 20-year-old federal requirement that food makers label their products for cholesterol content, adding a non-trivial amount to the cost of packaging. So much for untold gazillions’ worth of “no cholesterol” advertising aimed at health-conscious consumers.

Shed a tear for America’s egg industry, falsely accused of blocking the nation’s arteries. Per capita consumption of eggs, the yolks of which contain an average 186 milligrams of cholesterol, fell from 24 pounds in 1971 to 18 pounds in 1995, with only a modest recovery since then, according to the Agriculture Department.

There’s a lesson here for all of us, especially those who urge that this or that public policy be dictated by “the science.”

To be sure, that lesson is not that all science is as poor a guide to policy. Evolution, certainly, is established beyond a reasonable doubt, as is the link between tobacco and cancer.

Still, some science is bound to disappoint, or mislead, at significant social and financial cost, before it gets corrected. Unfortunately, consumers are poorly positioned to separate the wheat from the chaff.

There’s a limit to how much science we can understand on our own; we take the rest on faith, either because we think it’s advantageous, or because we see no practical alternative, or because people often defer to authority.

Doctors and researchers, authors of “medical miracles,” are more like a priesthood, or a cadre of sorcerers, than we generally admit. Their legitimacy is based on something real, and time-tested – the scientific method – but it also comes from the mystique of their diplomas and white coats.

And, like priests, even scientists can be led into error – whether through good faith, self-interest or simple “scientific inertia,” a synonym for conventional wisdom.

We’re doomed to rely on science; imperfect as it is, it beats the alternatives. The trick is for scientists to produce their work with appropriate humility, and for citizens to consume it with appropriate skepticism. For all the money, time and energy we wasted on mistaken beliefs about cholesterol over the past few decades, at least the error got corrected through continued research.

Precisely because it is, or aspires to be, value-free, science is better at describing social problems than solving them. Policymaking is all about value judgments and trade-offs. Science can prove that man-made climate change, for example, is real; the “right” way to address it is a matter of morality and politics.